1. Technical Field
The present invention relates to a liquid ejecting apparatus which includes a liquid ejecting head having nozzles and ejecting liquid from the nozzles onto a liquid-ejected medium on the basis of liquid ejection data, and a carriage carrying the liquid ejecting head and moving in the width direction of the liquid-ejected medium which is sent, and to a liquid ejecting method of the liquid ejecting apparatus.
In this application, in the liquid ejecting apparatus, recording apparatuses such as ink jet printers, line printers, photocopiers, and facsimiles shall be included. Here, in the line printer, for example, printers shall be included which each has a configuration in which rows of nozzles are provided to extend in a feed direction of the paper and a carriage having a recording head moves several times in the width direction of the paper when carrying out the recording.
2. Related Art
In the past, as shown in JP-A-2005-319635, a configuration has been made such that in the movement of the n-th time of a carriage, the stop position of the carriage is determined by considering the recording data in the movement of the next time, the (n+1)th time, of the carriage. Accordingly, it has been possible to minimize the loss of moving distance and the loss of moving time of the carriage when ink is not discharged. As a result, it has been possible to shorten the so-called throughput that is the required time from the start of the recording to the end of the recording per one sheet of paper.
However, if a stop position of the carriage is determined by considering the recording data in the movement of the next time, i.e., the (n+1)th time, of the carriage, there is a case where the carriage stops at a position where the nozzles formed in a recording head of the carriage face a side end of the paper. In such a case, there is a risk that powdery material such as paper dust, which is generated from the side end of the paper, adheres to the nozzles, so that poor discharge of ink in the nozzles occurs.
Shown in FIGS. 6A to 6C are diagrams showing adhesion amounts of the powdery material in the faces of recording heads 51 which are shown according to the stop positions of a carriage 50 which is considered by the invention. Of these, FIG. 6A is a schematic plan view showing a relationship between the row of nozzles of the recording head 51 and a side end (59 or 60) of paper 58.
Also, although two recording heads 51 are shown, actually, there are not two recording heads 51. This is for showing the positions of the respective recording heads 51, and actually, there is on only one recording head 51.
Also, FIG. 6B is a diagram showing the quantity of the powdery material on a face of the recording head 51 which has stopped at a position where the left side end 59 of the paper 58 in FIG. 6A and the space between the rows of nozzles face each other. Meanwhile, the vertical axis represents the quantity of the powdery material. On the other hand, the horizontal axis represents a position in a width direction on a face of the recording head 51. Further, FIG. 6C is a diagram showing the quantity of the powdery material on a face of the recording head 51 which has stopped at a position where the center of the paper 58 in FIG. 6A and the rows of nozzles face each other. The vertical axis and the horizontal axis are the same as those in FIG. 6B.
As shown in FIG. 6A, the recording head 51 is held by the carriage 50 and is provided so as to be able to move in a width direction with respect to a feed direction of the paper 58. Also, a total of six rows of nozzles (52 to 57), an A row to an F row in order from the left side, are formed in the recording head 51.
For example, as shown in FIG. 6A, the paper 58 is sent to the downstream side in the feed direction in a state where the recording head 51 has stopped at a position where the left side end 59 of the paper 58 and the space between the C row of nozzles 54 and the D row of nozzles 55 of the recording head 51 face each other. FIG. 6B shows an amount of the powdery material adhering to a face of the recording head 51 in such a case.
Also, the paper 58 is sent to the downstream side in the feed direction in a state where the recording head 51 has stopped at a position where the center of the paper 58 and the A row of nozzles 51 to the F row of nozzles 57 of the recording head 51 face each other. FIG. 6C shows an amount of the powdery material adhering to a face of the recording head 51 in such a case.
As shown in FIG. 6B, the adhesion amount of the powdery material such as paper dust in the space between the C row of nozzles 54 and the D row of nozzles 55, which faces the left side end 59 of the paper 58, is significantly large.
This is believed to be because slight vibrations are generated due to the sending of the paper 58, whereby paper dust is generated in the side end of the paper 58, and the generated paper dust is scattered up, thereby adhering to a face of the recording head 51. Also, the manner of distribution of the adhesion amount of the powdery material is considered to be close to a Gaussian distribution.
Also, as shown in FIG. 6C, the adhesion amount of the powdery material in the recording head 51 which faces the center of the paper 58 is very small compared to the case of FIG. 6B. This is believed to be because it is difficult for the powdery material such as paper dust to generate in the center of the paper 58, so that the adhesion amount to a face of the recording head 51 is small.
Also, a case where the paper 58 is sent to the downstream side in the feed direction in a state where the recording head 51 has stopped at a position where the right side end 60 of the paper 58 and the nozzle face of the recording head 51 face each other is the same as the case of a position where the left side end 59 and the nozzle face of the recording head 51 face each other. That is, there is a peak of distribution of the adhesion amount at a position which faces the side end. Since an amount and distribution of the powdery material adhering to a face of the recording head 51 are the same as those in FIG. 6B, illustration of the distribution is omitted.
From these points, it is understood that slight vibrations are generated due to the sending of the paper 58, whereby paper dust is generated in the side ends (59 and 60) of the paper 58, and the generated paper dust is scattered up, thereby adhering to a face of the recording head 51.
Also, shown in FIGS. 7A and 7B are sectional front views showing outlines of the structures of photographic paper and plain paper, each of which is an example of the liquid-ejected medium. Of these, FIG. 7A shows the photographic paper. On the other hand, FIG. 7B shows the plain paper.
As shown in FIG. 7A, photographic paper 61 has a front face coating layer 62, an ink absorbing layer 63, a base layer 64, and a back face coating layer 65 in order from the surface toward the back face. The front face coating layer 62 and the back face coating layer 65 are formed by a coating process such that they become the outermost layers of the surface and the back face for adjustment of gloss or the like, prevention of occurrence of a scratch, or the like.
Also, the ink absorbing layer 63 is provided at the surface side of the base layer 64 in order to increase the amount of ink that is absorbed, thereby expanding the range capable of reproducing colors. Further, the base layer 64 is provided so as to become the core of the photographic paper 61. The base layer 64 of the photographic paper 61 is constituted with resin as its main constituent. Here, the “main constituent” means, in the case of a composition which is composed of a plurality of materials, the material with the highest percentage among the plurality of materials.
On the other hand, as shown in FIG. 7B, plain paper 66 has a base layer 67 containing pulp as its main constituent. In the case of the plain paper 66, besides pulp, for example, pigments such as calcium carbonate are added for the purpose of increasing the degree of whiteness. Further, for example, fillers (a filling agent) such as clay, talc, or calcium carbonate are added for the purpose of achieving opacity, smoothness, weight increase, or the like of the medium.
Here, the photographic paper 61 of FIG. 7A and the plain paper 66 of FIG. 7B are compared with each other. In the photographic paper 61, the base layer 64 has a configuration composed mainly of resin, whereas in the plain paper 66, the base layer 67 has a configuration composed mainly of pulp. Therefore, compared to the photographic paper 61, the base layer 67 of the plain paper 66 comes apart more easily. For this reason, it is understood that compared to a side end 68 of the photographic paper 61, on a side end 69 of the plain paper 66, the powdery material is more easily generated from a cross-sectional surface.
Also, in contrast to the photographic paper 61, in the plain paper 66, the base layer 67 is not subjected to a coating process. For this reason, a process to maintain the material constitution of the base layer, which is generated due to a coating process in the side end 68 of the photographic paper 61, cannot be obtained in the side end 69 of the plain paper 66. Therefore, it is understood that compared to the side end 68 of the photographic paper 61, in the side end 69 of the plain paper 66, the powdery material is more easily generated from a cross-sectional surface.
In this manner, the amount of generation of the powdery material in the side end of the medium is thought to greatly vary with the nature of each type of medium. Moreover, an amount of the powdery material adhering to a face of the recording head is thought to greatly vary with the nature of each type of medium.